Enclosed-channel reactor method to manufacture catalysts or support materials

ABSTRACT

The present invention provides methods and designs of enclosed-channel reactor system for manufacturing catalysts or supports. Both of the configuration designs force the gaseous precursors and purge gas flow through the channel surface of reactor. The precursors will transform to thin film or particle catalysts or supports under adequate reaction temperature, working pressure and gas concentration. The reactor body is either sealed or enclosed for isolation from atmosphere. Another method using super ALD cycles is also proposed to grow alloy catalysts or supports with controllable concentration. The catalysts prepared by the method and system in the present invention are noble metals, such as platinum, palladium, rhodium, ruthenium, iridium and osmium, or transition metals such as iron, silver, cobalt, nickel and tin, while supports are silicon oxide, aluminum oxide, zirconium oxide, cerium oxide or magnesium oxide, or refractory metals, which can be chromium, molybdenum, tungsten or tantalum.

This application is a divisional of an application Ser. No. 13/948,499,filed on Jul. 23, 2013, now pending, which is based on, and claims thepriority benefit of Taiwan application no. 101143624, filed on Nov. 22,2012. The contents of each of the above-mentioned patent applications ishereby incorporated by reference herein in its entirety and made a partof this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention presents a method based on chemical vapordeposition reactions, particularly an enclosed-channel reactor systemand a method to manufacture catalysts or support materials on the basisof atomic layer deposition (ALD).

2. Description of the Prior Art

Catalysts are typically applied to increase reaction rate in variousprocesses with less energy consumption, such as fuel cells and hydrogenproduction by water splitting. Improving the surface area between gasphase and catalyst would be a key factor to improve the reaction rate.Therefore, to obtain well-dispersed and nanoscaled catalysts with largespecific area is crucial for catalytic reactions.

The catalytic reaction can be depicted as shown in FIG. 1(a). With thehelp of catalyst, reactant A will be transformed to product B in afaster and energy-efficient way. In order to prevent the participationof unwanted elements, the catalytic reaction is typically contained inthe enclosed-channel reactor as shown in FIG. 1(b), where the reactant Awill flow through. Accordingly, the catalyst should be coated on theinner surface of channel for the catalytic reaction, as shown in FIG.1(c). Furthermore, a thermally stable nanoscaled support, shown in FIG.1(d), would be needed to prevent the clustering of nanoscaled catalyst,at elevated temperature, leading to reduction of surface area forcatalytic reaction.

Conventionally, nanoscaled catalyst or support can be prepared byinjecting liquid precursor into channels by compressed air, followed byheating at elevated temperatures. However, it is difficult to uniformlydeposit the catalyst or support on channel surface with good dispersiondue to restriction of channel shape or size and poor precursorliquidity. Powder metallurgy is an alternative to prepare catalyst andsupport by co-sintering the liquid precursor. However, only a limitedamount of catalyst on the surface is available for catalytic reaction sothat the utilization efficiency of catalyst is low. Therefore, it wouldbe helpful to deposit well-dispersed nanoscaled catalyst or support onthe channel surface.

Vapor deposition is considered to deposit catalyst or support materialon the channel surface with a better dispersion. As shown in FIG. 2, thegaseous precursor would, however, tend to transport through peripheralpath Q1 of a reactor body 12 rather than inner path Q2 due to thedifference of gas conductance. The catalyst or support would tend todeposit on the surface along the outside path, which cannot serve asreaction area. Therefore, the utilization efficiency of catalyst grownby a conventional vapor deposition process would be low. Uses ofextended injection duration and high concentration may lead to a thickercoating along path Q2, but the cost would increase significantly.Therefore, it is crucial to improve the coating of catalyst or supporton the inner path Q2 with less consumption of precursor.

SUMMARY OF THE INVENTION

To improve coating uniformity with less consumption of precursors, thepresent invention utilizes vapor deposition technique with a cappingmechanism to force the precursors and purge gas to flow through theinner path of an enclosed-channel reactor.

The present invention is intended to use chemical vapor deposition forpreparation of catalyst, support or their mixture in an enclosed-channelreactor. Precursors of catalyst or support are injected into thechannels of the reactor body through the inlet cap and removed from theoutlet cap. Nitrogen, hydrogen or inert gas (helium, neon, or argon) istypically applied as a carrier gas to transfer less-volatile precursorsinto the channels. The precursors will transform to catalyst or supportunder adequate reaction temperature, working pressure, and gasconcentration.

The present invention is also intended to use atomic layer depositionfor preparation of catalyst, support material or their mixture in anenclosed-channel reactor. The first and second precursors of catalyst orsupport are separately and alternatively injected into the inlet cap andremoved from the outlet cap, between which a large amount of nitrogen,hydrogen or inert gas (helium, neon, or argon) is introduced as a purgegas to remove unreacted precursor and byproduct. The first and secondprecursors are called A and B, respectively, while the purge gas iscalled P. The sequential injection of A-P-B-P steps compose an ALDcycle. By repeating the ALD cycles, precursors will transform tocatalyst or support under adequate reaction temperature, workingpressure and gas concentration.

The present invention of an enclosed-channel reactor system comprises areactor body as well as an inlet cap and an outlet cap. The reactor bodywith a cylindrical or polygonal contour has a plurality of channelsinside, which act as the surface for catalytic reaction. The inlet capconnects with the reactor body at the upstream side of gas flow and hasconduit linking to the channels. The outlet cap has conduit linking tothe channels at the downstream side of gas flow and connects to a vacuumpump. Both contacts of inlet and outlet caps with the reactor body aresealed with an elastomer O-ring to achieve isolation from theatmosphere.

The present invention of an alternative enclosed-channel reactor systemcomprises a reactor body as well as a reactor enclosure and a reactorcap. The reactor body with a cylindrical or polygonal has a plurality ofchannels inside, which act as the surface for catalytic reaction. Thereactor enclosure that externally encloses the reactor body is connectedto a reactor cap which is either at the upstream side or downstream sideof gas flow. The contact between inlet and outlet caps is sealed with anelastomer O-ring to achieve isolation from the atmosphere.

In the present invention, inner channels in each of the above reactorscan be coated with catalyst, including noble metals, such as platinum,palladium, rhodium, ruthenium, iridium and osmium, or transition metals,such as iron, silver, cobalt, nickel and tin; or support materials,including silicon oxide, aluminum oxide, zirconium oxide, cerium oxide,wherein the support materials are capable of resisting high temperature;or refractory metals, which can be chromium, molybdenum, tungsten, ortantalum.

Based on the above enclosed-channel reactors, the present invention alsorefers to a method for preparing catalyst or support material by usingan ALD super cycle comprising two different ALD cycles. In the first ALDcycle, the first and second precursors of catalyst or support areseparately and alternatively injected into the reactor, between which alarge amount of nitrogen, hydrogen or inert gas (helium, neon, or argon)is introduced to remove unreacted precursor and byproduct. The first ALDcycle is composed of sequential injection of A-P-B-P steps. In thesecond

ALD cycle, the first precursor A is replaced by a third precursor A′.The second ALD cycle is therefore composed of sequential injection ofA′-P-B-P steps.

In the present invention, both of the first and second ALD cycles can beused to grow catalyst, including noble metals, such as platinum,palladium, rhodium, ruthenium, iridium and osmium, or transition metals,such as iron, silver, cobalt, nickel and tin; or support materials,including silicon oxide, aluminum oxide, zirconium oxide, cerium oxide;or refractory metals which can be chromium, molybdenum, tungsten, ortantalum.

In the above mentioned method using an ALD super cycle, the A-P-B-P andA′-P-B-P ALD cycles are repeated N and M times, respectively, to form analloy catalyst or support. Furthermore, the composition can becontrolled by using an optimum ratio, N/(N+M), under adequate reactiontemperature, working pressure and gas concentration.

These features and advantages of the present invention will be fullyunderstood and appreciated from the following detailed description ofthe accompanying Drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is (a) an illustration of catalytic reaction, (b) a schematicview of enclosed-channel reactor and enlarged views of channel surfacewith (c) catalyst and (d) support/catalyst.

FIG. 2 is a schematic view of a deposition chamber for deposition ofcatalyst or support material on the channel surface of a conventionalenclosed reactor.

FIG. 3 is a schematic view of the present invention of anenclosed-channel reactor system.

FIG. 4A is a schematic view of the present invention of anenclosed-channel reactor system.

FIG. 4B is a schematic view of the present invention of anenclosed-channel reactor system.

FIG. 5 is a schematic view illustrating an ALD cycles.

FIG. 6 is a schematic view illustrating a super ALD super-cycles.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An enclosed-channel reactor system 2 in the present invention, as shownin FIG. 3, comprises a reactor body 21, an inlet cap 22 and an outletcap 23. The reactor body 21 with a cylindrical or polygonal contour hasa plurality of channels 28 inside, which act as the surface forcatalytic reaction. The inlet cap 22 connects with the reactor body 21at the upstream side 25 of gas flow and has conduit linking to thechannels 28. The outlet cap has conduit linking to the channels ofreactor body 21 at the downstream side 26 of gas flow and to a vacuumpump on the other side. Both inlet cap 22 and outlet cap 23 contact thereactor body with an elastomer O-ring 24 stuffed into a groove 27 forisolation from the atmosphere, as shown in FIG. 3.

Another enclosed-channel reactor system 3 in the present invention, asshown in FIG. 4, comprises a reactor body 31, a reactor enclosure 32 anda reactor cap 33. The reactor body 31 with a cylindrical or polygonalcontour has a plurality of channels 37 inside, which act as the surfacefor catalytic reaction. The reactor enclosure 32 externally encloses thereactor body is connected to a reactor cap 33, which is either at theupstream side 25 or downstream side 26 of gas flow, as shown in FIGS. 4Aand 4B. The contact between reactor enclosure 32 and reactor cap 33 issealed with an elastomer O-ring 24 stuffed into a groove 27 to achieveisolation from the atmosphere.

FIG. 5 shows the flow rates of precursors A and B and purge gas P versustime in the ALD cycle of the present invention. A suitable number ofA-P-B-P ALD cycles are chosen for controlling the size of catalyst orsupport to obtain optimal catalyst efficiency.

Based on the above steps, 100 Å thick aluminum oxide support isdeposited on the channel surface of the enclosed-channel reactor system2 by using 100 ALD cycles at 200° C. Aluminum chloride, aluminum bromideor trimethylaluminum (TMA) is used as the first precursor while water isused as the second precursor.

Based on the above steps, 60 Å thick titanium dioxide catalyst is firstdeposited on the channel surface of the enclosed-channel reactor system2 by using 100 ALD cycles at 200° C. Titanium tetrachloride and waterare used as the first and second precursors, respectively. Secondly,platinum nanoparticles with a diameter of 40 Å are grown as aco-catalyst on the above titanium dioxide film by using 100 ALD cycles.Organoplatinum precursor (MeCpPtMe₃) and oxygen are used as first andsecond precursors, respectively.

FIG. 6 shows a typical relationship of flow rates of precursor A, A′,and B and purge gas P versus time in the ALD super-cycle of the presentinvention, containing two A-P-B-P cycles and one A′-P-B-P cycle.Furthermore, the numbers of A-P-B-P and A′-P-B-P, N and M, in theALD-cycle can be changed for controlling the composition of alloycatalyst or support to obtain optimal catalyst efficiency.

Based on the above steps, 100 Å thick aluminum oxide support is firstdeposited on the channel surface of the enclosed-channel reactor system2 by using 100 ALD cycles at 200° C. in which trimethylaluminum andwater are used as the first and second precursors, respectively.Secondly, PtRu₄ alloy catalyst particles with a diameter of 40 Å aregrown as catalyst on the above aluminum oxide film by using an ALDsuper-cycle consisting of 5 sub-cycles of A-P-B-P and 20 sub-cycles ofA′-P-B-P in which an organoplatinum precursor (MeCpPtMe₃), a rutheniumcomplex (Ru(Cp)₂) and oxygen are taken as precursor A, precursor A′ andprecursor B, respectively.

Methods and designs of enclosed-channel reactor system for manufacturingcatalyst or support in the present invention have the features incontrast to prior arts.

1. Catalyst and support material are assured to deposit on surface ofchannels by means of a forced gas flow passing through enclosedchannels.

2. Size of catalyst or support material, and composition of materials tobe mixed are controlled by using different numbers of ALD cycles andratios N/(N+M) in an ALD super cycle, respectively.

The present invention provides a better reactor design and method toimprove the utilization efficiency and reduce consumption andmanufacturing cost of catalyst.

What is claimed is:
 1. A method based on an enclosed-channel reactorsystem for manufacture of catalysts or support materials, said systemcomprising a reactor body provided with a plurality of enclosed channelsinside, an inlet cap connecting with the said reactor body at theupstream side and having an inlet end which links enclosed channels insaid reactor body, and an outlet cap connecting with the said reactorbody at the downstream side and having an outlet end which linksenclosed channels in said reactor body, said method comprising steps asfollows: injecting precursors of catalyst or support materials into saidenclosed channels of said reactor body through said inlet end; injectingan inert gas via said inlet end to purge said enclosed channels anddischarged from said outlet end for diluting or removing said residualprecursors; and completing deposition in said enclosed channels of saidreactor body for preparation of catalysts or support materials.
 2. Themethod based on said enclosed-channel reactor system for manufacture ofcatalysts or support materials according to claim 1, wherein saidprecursors are compounds of noble metals or transition metals.
 3. Themethod based on said enclosed-channel reactor system for manufacture ofcatalysts or support materials according to claim 2, wherein said noblemetals comprise platinum, palladium, rhodium, ruthenium, iridium orosmium.
 4. The method based on said enclosed-channel reactor system formanufacture of catalysts or support materials according to claim 2,wherein said transition metals comprise iron, silver, cobalt, nickel, ortin.
 5. The method based on said enclosed-channel reactor system formanufacture of catalysts or support materials according to claim 1,wherein said support materials are one oxide which is capable ofresisting high temperature.
 6. The method based on said enclosed-channelreactor system for manufacture of catalysts or support materialsaccording to claim 5, wherein said oxide which is capable of resistinghigh temperature is silicon oxide, aluminum oxide, zirconium oxide,cerium oxide.
 7. The method based on said enclosed-channel reactorsystem for manufacture of catalysts or support materials according toclaim 1, wherein said support materials are refractory metals.
 8. Themethod based on said enclosed-channel reactor system for manufacture ofcatalysts or support materials according to claim 7, wherein saidrefractory metal is chromium, molybdenum, tungsten or tantalum.
 9. Themethod based on said enclosed-channel reactor system for manufacture ofcatalysts or support materials according to claim 1, wherein said inertgas is helium, neon or argon.
 10. A method based on an enclosed-channelreactor system for manufacture of catalysts or support materials, saidsystem comprising a reactor body provided with a plurality of enclosedchannels inside, a reactor enclosure externally capping said reactorbody, allowing one end to be adjacent to one end of said reactor body,and having an outlet end shared by said enclosed channels, and a reactorcap which has one end linking said reactor enclosure's other end inorder to seal said reactor cap and said reactor enclosure and the otherend on which there is an inlet end linking said enclosed channels insaid reactor body, said method comprising steps as follows: injectingprecursors of catalysts or support materials into said enclosed channelsof said reactor body through said inlet end; injecting an inert gas viasaid inlet end to purge said enclosed channels and discharged from saidoutlet end for diluting or removing said residual precursors; andcompleting deposition in said enclosed channels of said reactor body forgrowth of catalysts or support materials.
 11. The method based on saidenclosed-channel reactor system for manufacture of catalysts or supportmaterials according to claim 10, wherein said precursors are compoundsof noble metals or transition metals.
 12. The method based on saidenclosed-channel reactor system for manufacture of catalysts or supportmaterials according to claim 11, wherein said noble metals compriseplatinum, palladium, rhodium, ruthenium, iridium, or osmium.
 13. Themethod based on said enclosed-channel reactor system for manufacture ofcatalysts or support materials according to claim 11, wherein saidtransition metals comprise iron, silver, cobalt, nickel, or tin.
 14. Themethod based on said enclosed-channel reactor system for manufacture ofcatalysts or support materials according to claim 10, wherein saidsupport materials are one oxide which is capable of resisting hightemperature.
 15. The method based on said enclosed-channel reactorsystem for manufacture of catalysts or support materials according toclaim 14, wherein said oxide which is capable of resisting hightemperature is silicon oxide, aluminum oxide, zirconium oxide, ceriumoxide.
 16. The method based on said enclosed-channel reactor system formanufacture of catalysts or support materials according to claim 10,wherein said support materials are one refractory metal.
 17. The methodbased on said enclosed-channel reactor system for manufacture ofcatalysts or support materials according to claim 16, wherein saidrefractory metal is chromium, molybdenum, tungsten or tantalum.
 18. Themethod based on said enclosed-channel reactor system for manufacture ofcatalysts or support materials according to claim 10, wherein said inertgas is helium, neon or argon.
 19. A method based on an enclosed-channelreactor system for manufacture of catalysts or support materials, saidsystem comprising a reactor body provided with a plurality of enclosedchannels inside, a reactor enclosure externally capping said reactorbody, allowing one end to be adjacent to one end of said reactor body,and having an outlet end shared by said enclosed channels, and a reactorcap which has one end linking said reactor enclosure's other end inorder to seal said reactor cap and said reactor enclosure and the otherend on which there is an inlet end linking said enclosed channels insaid reactor body, said method being on the basis of an ALD cycle withsteps as follows: injecting a first precursor into said enclosedchannels of said reactor body through said inlet end; injecting an inertgas via said inlet end to purge said enclosed channels and dischargedfrom said outlet end for diluting or removing said residual firstprecursor; injecting a second precursor into said enclosed channels ofsaid reactor body through said inlet end; and injecting another inertgas via said inlet end to purge said enclosed channels and dischargedfrom said outlet end for diluting or removing said residual secondprecursor.
 20. The method based on said enclosed-channel reactor systemfor manufacture of catalysts or support materials according to claim 19,wherein said inert gas is helium, neon or argon.
 21. The method based onsaid enclosed-channel reactor system for manufacture of catalysts orsupport materials according to claim 19, wherein said the thicknessincrease of catalysts or support materials is 0.5˜1.5 Å after one cycleALD reaction, and the growth rate of deposited catalyst or supportmaterial is linearly and positively proportional to cycle number of ALD.22. A method based on said enclosed-channel reactor system formanufacturing catalysts or support materials, said system comprising areactor body provided with a plurality of enclosed channels inside, areactor enclosure externally capping said reactor body, allowing one endto be adjacent to one end of said reactor body, and having an outlet endshared by said enclosed channels, and a reactor cap which has one endlinking said reactor enclosure's other end in order to seal said reactorcap and said reactor enclosure and the other end on which there is aninlet end linking said enclosed channels in said reactor body, saidmethod being on the basis of an ALD super-cycle with steps as follows: afirst cycle: a. injecting a first precursor into said enclosed channelsof said reactor body through said inlet end; b. injecting an inert gasvia said inlet end to purge said enclosed channels and discharged fromsaid outlet end for diluting or removing said residual first precursor;c. injecting a second precursor into said enclosed channels of saidreactor body through said inlet end; d. injecting an inert gas via saidinlet end to purge said enclosed channels and discharged from saidoutlet end for diluting or removing said residual second precursor; anda second cycle: e. injecting a third precursor into said enclosedchannels of said reactor body through said inlet end; f. injectinganother inert gas via said inlet end to purge said enclosed channels anddischarged from said outlet end for diluting or removing said residualthird precursor; g. injecting a second precursor into said reactor bodythrough said inlet end; h. injecting an inert gas via said inlet end topurge said enclosed channels and discharged from said outlet end fordiluting or removing said residual second precursor; wherein said firstcycle and said second cycle for growth of catalysts or support materialsare conducted N and M times, respectively.
 23. The method based on saidenclosed-channel reactor system for manufacturing catalysts or supportmaterials according to claim 22, wherein said inert gas is helium, neonor argon.
 24. The method based on said enclosed-channel reactor systemfor manufacturing catalysts or support materials according to claim 22,wherein said first cycle and said second cycle in which there are stepsalternately or repeatedly practiced are conducted N and M times,respectively.
 25. The method based on said enclosed-channel reactorsystem for manufacturing catalysts or support materials according toclaim 22, wherein said first cycle and said second cycle, which comprisesteps alternately or repeatedly conducted N and M times respectively,are able to control said composition of catalysts.
 26. A method based onsaid enclosed-channel reactor system for manufacturing catalysts orsupport materials, said system comprising a reactor body provided with aplurality of enclosed channels inside, a reactor enclosure externallycapping said reactor body, allowing one end to be adjacent to one end ofsaid reactor body, and having an outlet end shared by said enclosedchannels, and a reactor cap which has one end linking said reactorenclosure's other end in order to seal said reactor cap and said reactorenclosure and the other end on which there is an inlet end linking saidenclosed channels in said reactor body, said method being on the basisof an ALD cycle with steps as follows: injecting a first precursor intosaid enclosed channels of said reactor body through said inlet end;injecting an inert gas via said inlet end to purge said enclosedchannels and discharged from said outlet end for diluting or removingsaid residual first precursor; injecting a second precursor into saidenclosed channels of said reactor body through said inlet end; injectingan inert gas via said inlet end to purge said enclosed channels anddischarged from said outlet end for diluting or removing said residualsecond precursor; and
 27. The method based on said enclosed-channelreactor system for manufacturing catalysts or support materialsaccording to claim 26, wherein said inert gas is helium, neon or argon.28. The method based on said enclosed-channel reactor system formanufacturing catalysts or support materials according to claim 26,wherein said the thickness increase of catalysts or support materials is0.5˜1.5 Å after one cycle of ALD reaction. The growth rate of depositedcatalyst or support material is linearly and positively proportional tocycle number of ALD.
 29. A method based on said enclosed-channel reactorsystem for manufacturing catalysts or support materials, said systemcomprising a reactor body provided with a plurality of enclosed channelsinside, a reactor enclosure externally capping said reactor body,allowing one end to be adjacent to one end of said reactor body, andhaving an outlet end shared by said enclosed channels, and a reactor capwhich has one end linking said reactor enclosure's other end in order toseal said reactor cap and said reactor enclosure and the other end onwhich there is an inlet end linking said enclosed channels in saidreactor body, said method being on the basis of a super ALD cycle withsteps as follows: a first cycle: a. injecting a first precursor intosaid enclosed channels of said reactor body through said inlet end; b.injecting an inert gas via said inlet end to purge said enclosedchannels and discharged from said outlet end for diluting or removingsaid residual first precursor; c. injecting a second precursor into saidenclosed channels of said reactor body through said inlet end; d.injecting an inert gas via said inlet end to purge said enclosedchannels and discharged from said outlet end for diluting or removingsaid residual second precursor; and a second cycle: e. injecting a thirdprecursor into said enclosed channels of said reactor body through saidinlet end; f. injecting an inert gas via said inlet end to purge saidenclosed channels and discharged from said outlet end for diluting orremoving said residual third precursor; g. injecting a second precursorinto said reactor body through said inlet end; h. injecting an inert gasvia said inlet end to purge said enclosed channels and discharged fromsaid outlet end for diluting or removing said residual second precursor;and wherein said first cycle and said second cycle for preparation ofcatalysts or support materials are conducted N and M times,respectively.
 30. The method based on said enclosed-channel reactorsystem for manufacturing catalysts or support materials according toclaim 29, wherein said inert gas is helium, neon or argon.
 31. Themethod based on said enclosed-channel reactor system for manufacturingcatalysts or support materials according to claim 29, wherein said firstcycle and said second cycle in which there are steps alternately orrepeatedly practiced are conducted N and M times, respectively.
 32. Themethod based on said enclosed-channel reactor system for manufacturingcatalysts or support materials according to claim 29, wherein said firstcycle and said second cycle, which comprise steps alternately orrepeatedly conducted N times and M times, respectively, are able tocontrol said catalysts and ratios of deposits.